This invention relates generally to a fiber optic sensor that includes a pair of multiple layer spiral-wound optical fiber coils on opposite sides of a flexural disk with the optical fiber coils being included in an interferometer. Still more particularly, this invention relates to a fiber optic sensor having an elastomeric material arranged to dampen motion resulting from high quality factor (Q) resonances and to limit the maximum travel of the flexural disk in response to acceleration.
The invention provides a technique for damping vibrations in a flexural disk fiber optic sensor. The invention also provides shock snubbing to prevent damage flexural disk fiber optic sensor upon exposure to high levels of shock and vibration. The invention uses tubing made from a commonly available elastomeric material with known damping properties in a shear damper configuration. The invention provides a significant increase in the system damping with a corresponding Q reduction down to 6 or less, which provides adequate margin to perform within an acceptable operational frequency band.
A fiber optic sensor according to the present invention comprises a flexural disk having a pair of fiber optic coils mounted on opposite sides thereof and connected together to form an interferometer that produces an output signal in response to acceleration of the flexural disk. The fiber optic sensor includes a housing having first and second end plates with a sidewall extending between them. The sidewall is formed to have an inwardly facing groove in which an outer edge portion of the flexural disk is mounted. A support member extends between oppositely facing portions of the first and second end. plates and through a central passage in the flexural disk. A damping member is mounted on the central support member and arranged to exert a radial force on an inner edge of the central passage in flexural disk to lock it in place therein to dampen longitudinal vibrations of the flexural member and thereby control the output signal amplitude over a selected frequency range.
The damping member is preferably mounted at a central region of the support member and restrained against lengthwise motion relative to the support member.
The support member preferably includes a groove in which the damping member is mounted. The damping member is formed of an elastomeric material and is axially compressed between end edges of the groove such that the damping member is expanded radially and forced against the inner edge portion of the flexural disk.